<template>
  <form class="validate-from-container">
    <slot name="default"></slot>
    <div class="submit-area" @click.prevent="submitForm">
      <slot name="submit">
        <!-- 什么都不填 显示默认内容 -->
        <button type="button" class="btn btn-primary">提交</button>
      </slot>
    </div>
  </form>
</template>

<script lang="ts">
import { defineComponent, onUnmounted } from "vue";
import mitt from "mitt";
type ValidateFunc = () => boolean;
export const emitter = mitt();  // 实例化 mitt
export default defineComponent({

  emits: ["form-submit"],

  setup(props, context) {

    let funcArr: ValidateFunc[] = [];
    
    const submitForm = () => {
      // 循环执行数组 得到最后的验证结果
      const result = funcArr.map((func) => func()).every((result) => result);
      
      context.emit("form-submit", result);
    };
    
    // 将监听得到的验证函数都存到一个数组中
    const callback = (func?: ValidateFunc) => {
      if (func) {
        funcArr.push(func)
      }
    }
    
    // 添加监听
    emitter.on("form-item-created", callback);

    onUnmounted(() => {
      // 删除监听
      emitter.off("form-item-created", callback);
      funcArr = [];
    });
    return {
      submitForm,
    };
  },
});
</script>